In commercial air conditioners, such as multi-air conditioner or modular air conditioners, one outdoor unit system is connected with multiple indoor unit systems, and a flow control valve is required to be mounted in a refrigerant loop of each indoor unit for cutting off refrigerant or adjusting the flow. The flow control valve is required to be capable of being adjusted to any opening degree and acting stably. Further, since the refrigerant loop of each indoor unit needs one flow control valve, the flow control valve is required to meet the requirement of minimization and large-capacity.
Currently, the flow control valve is generally a pilot control valve, and a valve core of the pilot valve is powered by a motor, and a main valve port is opened or closed by a main valve core and a valve core of the pilot valve cooperatively. However, when the pilot control valve opens the main valve port, the opening area is increased sharply, thus the flow changes sharply. That is to say, the pilot control valve cannot adjust the flow precisely.
For precisely adjusting the flow of the refrigerant, a direct-acting control valve may be employed. In a conventional direct-acting control valve, a screw rod is connected to and driven by an output shaft of a motor via a gear system, and the screw rod is cooperated with a nut by screw threads. The nut is connected with a valve core and is limited in position to allow the nut to be slidable along an axial direction of the screw rod but unable to be rotated in a circumferential direction of the screw rod. In operation, the motor starts, and an output shaft of the motor rotates, and the rotation is transmitted to the screw rod via the gear system, and with the rotation of the screw rod, the nut slides in the axial direction, which allows the valve core to slide in the axial direction, and further achieves the purpose of adjusting an opening degree of the valve port.
Since in the commercial air-conditioners such as multi-air conditioner or modular air conditioners, the area of the valve port of the flow control valve is required to be large, thus requiring a large driving force, and if the direct-acting control valve is adopted, a large size motor must be used for acquiring the large driving force, thus, the size of the control valve is excessively large, thus, not only the cost is increased, but also mounting and detaching are inconvenient.
In another kind of conventional direct-acting control valve, a screw rod is fixed to a rotor of a motor, and is cooperated with a nut by screw threads, and a lower end of the screw rod is directly cooperated with a valve core, and the nut is fixed to a valve seat. In operation, the screw rod is rotated by the rotor of the motor, and since the screw rod is cooperated with the nut by screw threads and the nut is fixed, the screw rod may further be moved axially by the rotor, thus further allowing a valve core to open or close the valve port. However, when this kind of direct-acting control valve operates, the position of the rotor changes with respect to an axial center of the coil component due to an axial motion of the rotor, thus the rotor cannot be kept at the axial center of the coil component, which further reduces the driving force, and also. The size of the motor is also required to be increased for opening and closing a valve port with a large diameter.
In view of this, a technical issue to be addressed by those skilled in the art presently is to improve a direct-acting control valve, through which a valve port with a large diameter can be opened and closed by a small-sized motor.